Our 2004 Power Mac G5 (Pre SMU: it has a PMU reset button) went a bit funny before Christmas and started complaining about incompatible RAM (three blinks of the Power LED) It has three pairs of RAM sticks so I kicked off by trying only 1 pair with the same result, then a different pair with the same result. It then occurred to me that the CMOS battery might be getting a bit long in the tooth so I ordered a new one and replaced it. I then discovered resetting the PMU on the the motherboard, which did get a result for a short period before it gave up again.

Does anyone have any thoughts on this or is our G5 now a glorified paperweight?

__________________-MacBook Pro 15" 2.2GHz Santa Rosa 4GB 320gb 7200rpm (slightly dented from having a shelf land on it and from a rather unfortunate tumble from the table)
-OS 10.5.8 (XBench score 134)

__________________-MacBook Pro 15" 2.2GHz Santa Rosa 4GB 320gb 7200rpm (slightly dented from having a shelf land on it and from a rather unfortunate tumble from the table)
-OS 10.5.8 (XBench score 134)

My dual 1.8ghz experienced the same problem. Turned out to be faulty memory slots and not the memory itself. I guess the soldered connections to the logic board fractured? I was able to apply pressure to the slots and then reinsert the memory and it would run for days/weeks before it would "fail" again.

Is this OEM RAM or 3rd party? If 3rd party does it also happen w/ the OEM RAM too? That should give you an indication if the issue is w/ the RAM or the machine. Macs are known to be picky about RAM but if the OEM sticks don't register then it's something wonky w/ the machine.

If you can get the machine too boot off CD try the hardware test tool and see what it reports.

@orange, yup, I'd feared as much, but I was hoping there was something that I'd missed. I'll have a last try using different banks, but it sounds like the Motherboard needs mending with a new one.

@chupa, good thought, yes some of it is third party, but I've tried it with just the OEM and it just wasn't having any of it.

Bit of fishing on ebay due methinks.

__________________-MacBook Pro 15" 2.2GHz Santa Rosa 4GB 320gb 7200rpm (slightly dented from having a shelf land on it and from a rather unfortunate tumble from the table)
-OS 10.5.8 (XBench score 134)